Lower BaffleLower Baffle

Robert Besuner

26 August 2004

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Background/PurposeBackground/Purpose

• This study follows on to 12 August study of the Spacecraft Interface/Handling Ring.— In that study, the ring was assumed to be separate from lower baffle.— Main purpose of that study was to look at how the various

components of the observatory might be supported on the ground.

• Discussions indicate it’s preferable to make the ring be integral with the lower baffle.— More structurally efficient.— Should not require much delta T or thermal isolation from

spacecraft.

• General requirement for lower baffle design:— Should have removable access panels to allow ample access to lower

optics bay.— Remaining structure should be spartan, but still able to handle

expected ground loads.— Meet launch load requirements with access panels in place.— Closes out the aft end of the telescope (only vaguely addressed here).

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Lower Baffle, Closeouts in PlaceLower Baffle, Closeouts in Place• Aluminum assembly,

except Ti thermal standoffs.

• Upper and lower rings are nominally 150mm x 75mm x 3mm angle sections.

• Lower ring is 6mm thick by opening (purple).

• Columns are 100mm x 75 mm x 3mm box sections, with gussets.

• Closeouts are 1mm thick.

• 79.0kg total:• 29.7kg lower ring• 18.7kg upper ring• 19.3kg columns• 11.3kg closeouts

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Lower Baffle, Closeouts RemovedLower Baffle, Closeouts Removed• Aluminum assembly,

except Ti thermal standoffs.

• Upper and lower rings are nominally 150mm x 75mm x 3mm angle sections.

• Lower ring is 6mm thick by opening (purple).

• Columns are 100mm x 75 mm x 3mm box sections, with gussets.

• Closeouts are 1mm thick.

• 79.0kg total:• 29.7kg lower ring• 18.7kg upper ring• 19.3kg columns• 11.3kg closeouts

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Lower Baffle, OTA DummyLower Baffle, OTA Dummy• Aluminum assembly,

except Ti thermal standoffs.

• Upper and lower rings are nominally 150mm x 75mm x 3mm angle sections.

• Lower ring is 6mm thick by opening (purple).

• Columns are 100mm x 75 mm x 3mm box sections, with gussets.

• Closeouts are 1mm thick.

• 79.0kg total:• 29.7kg lower ring• 18.7kg upper ring• 19.3kg columns• 11.3kg closeouts

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Lower Baffle, OTA, Upper BaffleLower Baffle, OTA, Upper Baffle• Aluminum assembly,

except Ti thermal standoffs.

• Upper and lower rings are nominally 150mm x 75mm x 3mm angle sections.

• Lower ring is 6mm thick by opening (purple).

• Columns are 100mm x 75 mm x 3mm box sections, with gussets.

• Closeouts are 1mm thick.

• 79.0kg total:• 29.7kg lower ring• 18.7kg upper ring• 19.3kg columns• 11.3kg closeouts

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Lower Baffle, OTA, Upper Baffle, RadiatorLower Baffle, OTA, Upper Baffle, Radiator

• Aluminum assembly, except Ti thermal standoffs.

• Upper and lower rings are nominally 150mm x 75mm x 3mm angle sections.

• Lower ring is 6mm thick by opening (purple).

• Columns are 100mm x 75 mm x 3mm box sections, with gussets.

• Closeouts are 1mm thick.

• 79.0kg total:• 29.7kg lower ring• 18.7kg upper ring• 19.3kg columns• 11.3kg closeouts

8

Lower Baffle, OTA, Upper Baffle, RadiatorLower Baffle, OTA, Upper Baffle, Radiator

• Aluminum assembly, except Ti thermal standoffs.

• Upper and lower rings are nominally 150mm x 75mm x 3mm angle sections.

• Lower ring is 6mm thick by opening (purple).

• Columns are 100mm x 75 mm x 3mm box sections, with gussets.

• Closeouts are 1mm thick.

• 79.0kg total:• 29.7kg lower ring• 18.7kg upper ring• 19.3kg columns• 11.3kg closeouts

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Lower Baffle DetailsLower Baffle Details

3mm thick columns/gussets

6mm thick angle

3mm thick angle

3mm thick gussets

8mm thick mounting/handling

surfaces

1.5mm thick Ti thermal standoffs

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Deformation in 1g held by GSEDeformation in 1g held by GSE(baffle displacement~2.6mm)(baffle displacement~2.6mm)

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Baffle/OTA Assembly Mode 1, 20HzBaffle/OTA Assembly Mode 1, 20Hz

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Baffle/OTA Assembly Mode 2, 23HzBaffle/OTA Assembly Mode 2, 23Hz

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Material Safety FactorsMaterial Safety Factors

loading orientationTi mounts Al parts

horizontal 15 4.7vertical 54 8.5

2g lateral 12 126.5g axial 11 7.1

Launch accelerations (closeouts in place)

yield safety factors

telescope and baffle supported by GSE (no closeouts)

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ConclusionConclusion

• Lower baffle assembly shown here is mechanically viable.

• Complete closing out of light needs to be addressed.

• Thermal performance should be confirmed.